German Patent Publication (DE-OS) 2,641,828 (Mueller et al.), published on Mar. 23, 1978, describes an automatic screw gun capable of driving screws that are supplied to the gun by a belted screw supply. The screw gun with its magazine in which the belted screw supply is held, are portable. The belted screw supply comprises a belt with a belt backing to which belt loops are secured. Each belt loop holds one screw. More specifically, the belt loop extends around the screw shaft.
A belt feed advance mechanism feeds the screw carrying belt stepwise so as to bring the lead screw into axial alignment with the screw driver blade. As the screw feed advance progresses, the screw holding loop is torn open, whereby portions of the belt and/or of the loop may get lodged between the screw head and the work piece. The result is undesirable, especially where fine or easily marred work piece surfaces are involved.